The Millennium Ecosystem Assessment (MA) has outlined a clear logic: natural resources provide ecosystem services that contribute to human well-being, from nutrient cycling and carbon sequestration to recreational experiences. These ecosystem services are under constant threat from human activities. Through their actions, humans realise economic gains but also decrease their chances of enjoying sustained well-being for future as well as current generations. Economics can help integrate such losses of ecosystem services into decision making, by clarifying the synergies and trade-offs that come from land and ecosystem management. However, the science of ecosystem services is still in its infancy and methods vary wildly.

Ecosystem Services: The Risk of Success

One result of the MA process is that the popularity of the ecosystem services concept has taken flight, both in science and policy-making. This is due to its popularisation through attempts to express changes in natural processes and resources in monetary values. The current popularity of ecosystem valuation, however, may have pushed other aspects of the ecosystem services concept to the background.

Scientific studies to inform policy-makers abound, but the science of ecosystem services may not be fully ready. Recent studies frequently apply the concept in a vague, simplistic or even misleading manner. This point is illustrated by existing debates on the principles of the ecosystem services concept as well as its use in research. Recent publications suggest various ways to implement the ecosystem services concept in scientific studies. These discussions provide valuable conceptual ideas for improving ecosystems research, but lack practical suggestions for implementing them. As a result, conceptual progress in ecosystem science remains largely at the philosophical level. This is on the one hand a creative scientific process, but on the other hand we risk getting lost in discussions on concepts and fail to provide actors and stakeholders with robust indicators and arguments for development of political instruments and to support decision making. What is needed, however, to strengthen the political relevance of the ecosystem services concept are practical suggestions and recommendations.

Recent Challenges

These discussions are continued for instance within conceptualizing of the follow-up process of the Millennium Ecosystem Service Assessment. With the following five items CBD gives a summary on the recent lack of research and development (see UNEP/CBD/COP/9/INF/26)

Gaps in ecosystem services knowledge base. More needs to be known about the interdependence of ecological and social systems for human well-being, including the way ecosystems function, their response to human pressure, and their relationship to biodiversity. Other than those traded in markets, few ecosystem services are routinely monitored.

Operational tools and methodologies. Availability of working models for use by policy-makers to analyze ecosystem services and their trade-offs with development policies and resource allocations, is limited.

Insufficient attention to sub-global assessments. Very few developing country sub-global assessments were adequately funded, resulting in the significant discrepancy in the quality of sub-global assessment products.

Limited economic analysis. The MA fell short of defining convincing economic values of ecosystem services and, in particular, of the regulating and cultural services which could be used to evaluate the trade-offs with conventional development strategies.

Lack of periodic assessments. No permanent body or process exists to conduct periodic assessments of the status of ecosystem services to monitor and track changes in those services and their impacts on human well-being.

Limited awareness and understanding among decision-makers on the MA findings and the concept of ecosystem services. Ecosystem services are a new concept to most decision-makers. As a result, there is limited capacity to apply the ecosystem services framework and work proactively on incorporating ecosystem service considerations into development strategies.

On the one hand, these statements are fully understandable as there in line with well-known statements from stakeholders, scientist or policymakers. Some of these statements on the other hand are clearly surprising. For instance, environmental science can look back on a successful history of ecosystem research that is fully capable of an integrated approach to analyze multiple feedbacks in ecosystems and to study their behaviour in a quantitative view using models that are supposed to be taken up by decision makers. However, in concert these statements show that a collaborate action from all participants (stakeholders and scientist) needs to be taken to make the concept of Ecosystem Services applicable as a concept of science-policy interface.

Specific Recommendations

To provide consistent policy recommendations, we propose that researchers consider four issues that summarise the holistic perspective of the Ecosystem Services concept:

ensure biophysical realism of ecosystem service models;

provide information on trade-offs between Ecosystem Services under changing policy;

Whilst not every research project can be large and comprehensive, it is important that even in small projects the implications of these issues are discussed, if not addressed.

Biophysical realism

Measurement, modelling and monitoring of ecosystem services is the foundation for sustainable use of biodiversity, ecosystems and natural resources in general. A considerable number of recent ecosystem service studies make use of simple (proxy) indicators for variables that are assumed to reflect ecosystem processes mostly related to land use or even land cover data. While some simplification is needed to inform policy makers, oversimplification of ecosystems is unsatisfactory for a comprehensive system description. Ecosystem services research thus needs to strike a delicate balance between ecological realism and ease-of-use.

Two aspects of realism in modelling of ecosystem services are: quantification of uncertainties that arise from data and model structure and a systems perspective on ecosystem processes. The conflict in modelling ecosystem services is clear: specialists on specific processes may dismiss models with simple descriptions of multiple ecological functions, but it is the latter models that are useful in shaping policies for natural resource management. These models help inform and convince policy makers. Arguably, model-based assessments of ecosystem services provide more consistent insights into the ecosystem impacts of human actions than expert knowledge. However, scientifically satisfactory off-the-shelf solutions to ecosystem service modelling do not yet exist, requiring careful consideration of local conditions. If insights are lost on policy makers because the models are not understood, then these insights are of little help. With efforts to systematically simplify models to the right degree, e.g. to tailor model to the right degree of complexity, ecosystem services research can take a significant step towards supplying policy makers with dependable and useable results.

Regional trade-offs

Ecosystem services are not independent of one another and policies targeting one service may well affect spatio-temporal patterns of others. Yet many ecosystem studies focus only on a small number of selected services and therefore cannot show these ecological knock-on effects of human behaviour. Clearly illustrating these interactions and their impacts on human welfare constitutes a crucial step forward for ecosystem services. Models that analyse trade-offs in the provision of ecosystem services are still few and far between, which seems to undermine the holistic nature of the ecosystem service concept. This shortcoming furthermore implies that often policy decisions will be made based on a narrow range of information, on the core aspects, which the ecosystem services concept tries to avoid. Ecosystem service models that take a holistic approach could play an important role in helping policy makers understand local welfare impacts of their behaviour that they may not have considered otherwise.

Off-site effects

Ecosystem processes are coupled at small as well as large scales, both temporally and spatially. The temporal management of ecosystem services is an important issue, but many studies do not even consider consequences of local decisions on far-away ecosystem (‘off-site effects’), despite explicit calls by governments. So far the consideration of off-site effects has been virtually absent in the ecosystem services literature. Effects of human behaviour on the provision of ecosystem services elsewhere are real, yet few approaches exist that enable policy-makers to deal with this issue. Ecological and water footprint analyses are steps in the right direction, but these traditionally economic methods need to be refined and extended to more ecosystem services. Standards for the dependable accounting of off-site effects need to be developed, which is likely to require involvement of both local and international stakeholders. Such methods would provide crucial contributions to the development of new instruments for managing ecosystem services at the global scale.

Stakeholder involvement

One characteristic of the ecosystem services concept is that human appreciation of ecosystem processes is crucial: ecosystem functions become ecosystem services when they benefit humans. This implies that research into the management of ecosystem function requires stakeholder involvement at every stage of an ecosystem services assessment. However, stakeholders are typically involved in evaluating outcomes of ecosystem models. Where the development of scenarios and options for ecosystem policies is concerned, the role of stakeholders is usually non-existent. The so-called ‘ownership’ of policy options is crucial to sustainable management of ecosystems and the services they provide.

It is imperative that researchers recognise that stakeholders determine what the relevant ecosystem services are, that they rank both local and global ecosystem services, and that they support solutions that are suggested by modelling efforts. This support is crucial, as markets will evolve, which may leave the same ecosystem service equally valuable, but in a completely different economic setting. Such changes would require a re-evaluation of the indicators of ecosystem services. Involving stakeholders into ecosystem service research requires that researchers account for this extremely diverse set of cultural, economic and environmental conditions at all stages of developing new policy options.

Conclusions

Human kind experiences that - besides the limitation of our fossil resources - renewable resources are over harvested and ecosystems’ functioning is threatened in a way that formerly infinite resources such as pollination services became scarce. And this is why those services implicitly are valued and labelled with a price. Against this background, ecosystem services research is currently at a crossroads: policy makers have received the message that ecosystem service proponents have been putting out for several years now and now scientists need to deliver robust results for the development of new instruments for changing economies and societies. Research approaches, however, currently vary widely. Researchers need to consolidate the progress made and develop a consistent framework for designing and assessing policy options for the sustainable use of natural resources. Discussions on the implementation of the ecosystem services concept in policy-oriented research remain on a conceptual level. The goal is not to prescribe the methods, but to show that a holistic research approach to ecosystem services is possible and need not be overly complex.